Ever since the electronic computer became a technological reality, it has been evident that it would also be technically possible to store and process pattern information in a pattern sewing machine according to the same principles as in an electronic computer, using a pattern memory.
But in a sewing machine there is the problem that the signals emitted by such an electronic control circuit must be transformed into mechanical movement so that the resetting of the feed or needle-bar movements will take place. Such transformation can, in principle, be made in many different ways, but practical working devices have only recently been constructed.
There remains an unfulfilled need to establish a practical and efficient means for accessing control words from the pattern memory. A generalized system for accessing the pattern memory is shown in FIG. 1, for the purpose of illustrating the functions which must be performed. From an entirely general standpoint, it contains, first of all, the pattern memory 1 whose outputs control the mechanical pattern mechanism 2. The inputs of a standard memory circuit are, in order to obtain the lowest possible number of connections, always binary-coded, that is to say if the memory has space for 1024 code words, for example, than the memory will have 10 address leads. In order to select in the correct sequence, the codes stored in the pattern memory 1 which belong to a certain pattern, a device is required which can change the address word signals on the abovementioned address leads, during each machine revolution, so that correct control information is always present at the outputs of the pattern memory 1 for each stitch. This might be done, for example, with a counter circuit 3, whose outputs will constitute the pattern memory addressing, the computer being stepped in relation to the stitch being made. In order that this counter or addressing device 3 will begin generating the group of addresses relating to the code word of the selected pattern, the counter 3 must be pre-adjusted with a starting address selected for the actual pattern. These starting addresses must therefore be stored in a special address memory 4, in which a specific starting address code word is activated by the selection of the desired pattern seam. Finally, there must be a reset circuit 5, for the end of the pattern cycle, so that the addressing device 3 in some way will be made to repeat, and any desired number of consecutive pattern images can be sewn. It is not obvious to find the technical solution of this problem, but this invention presents one solution and constitutes an improvement of priorly known control devices of the aforementioned kind. Control circuits designed in accordance with the theory here described and built of standard components are assembled of a plurality of such components in which the necessary functions are carried out one by one. However, if the functions are assembled on one single semiconductor crystal arize alternative solutions, and the inventive idea as described in the following is developed on this background.